Repair and Retrofit of Unreinforced Masonry Structures

1996 ◽  
Vol 12 (4) ◽  
pp. 903-922 ◽  
Author(s):  
Teymour Manzouri ◽  
Michael P. Schuller ◽  
P. Benson Shing ◽  
Bernard Amadei
Keyword(s):  
Shear Wall ◽  
Unreinforced Masonry ◽  
Masonry Structures ◽  
Grout Injection ◽  
Before And After ◽  
Strength And Stiffness ◽  
Grouting Materials ◽  
Material Tests ◽  
Strength And Ductility ◽  
Comprehensive Study

A comprehensive study was conducted to evaluate the efficacy of different repair and retrofit techniques for unreinforced masonry (URM) structures. The study was to identify suitable grouting materials and procedures for the repair and retrofit of URM structures, quantify the efficacy of different repair and retrofit techniques, and develop analysis tools to evaluate the performance of masonry structures before and after retrofit. To this end, a number of grouting materials and procedures were evaluated with material tests, masonry component tests and shear wall tests. The experimental results indicate that the strength and stiffness of damaged walls can be fully restored with grout injection. Furthermore, the strength and ductility of a URM wall can be greatly enhanced by the introduction of steel reinforcement.

scholarly journals In-plane retrofitting of masonry structures by using GFRP strips in the Bedjoints

2021 ◽  
Author(s):  
Fathollah Osmanzadeh ◽  
Elshan Ahani ◽  
Behzad Rafezy ◽  
Mir Naghi Mousavi
Keyword(s):  
Ductile Failure ◽  
Unreinforced Masonry ◽  
Masonry Wall ◽  
Masonry Structures ◽  
Clay Bricks ◽  
Historical Structures ◽  
Before And After ◽  
Lateral Strength ◽  
Historical Masonry ◽  
Strength And Stiffness

Abstract Many unreinforced masonry structures were vulnerable in the past earthquakes and required retrofitting. However, the vulnerability of masonry structures could solve by providing numerous retrofitting approaches, scarcity of appropriate methods that may provide a solution for the historical masonry structures with lesser effects on their façade is vehemently sensible. In this study, two one-third scale masonry wall specimens made by clay bricks were tested under constant vertical and cyclic lateral loading. The specimens consist of an unreinforced wall and a wall retrofitted by GFRP strips. This study investigates the seismic behavior of unreinforced masonry walls before and after using GFRP strips on their bedjoints. To this purpose, various patterns of using GFRP strips have been studied by simplified micro-modeling. The consequence indicates that the proposed retrofitting technique could improve the lateral strength and stiffness of the unreinforced masonry wall along with a considerable increase in the energy dissipation and ductility content, which leads to making a change in the behavior of the wall from brittle to ductile failure. The proposed method could apply to the modern historical structures in which cement mortar has been used as an adhesive between the masonry layers.

Shaking Table Tests on Multi-Leaf Stone Masonry Structures: Analysis of Stiffness Decay

2010 ◽  
Vol 133-134 ◽  
pp. 647-652 ◽  
Author(s):  
Nicola Mazzon ◽  
Cano M. Chavez ◽  
Maria Rosa Valluzzi ◽  
F. Casarin ◽  
Claudio Modena
Keyword(s):  
Dynamic Behaviour ◽  
Shaking Table ◽  
Stone Masonry ◽  
Mode Shapes ◽  
Masonry Structures ◽  
Shaking Table Tests ◽  
Grout Injection ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Before And After

The influence of the natural hydraulic lime-based grout on the dynamic behaviour of injected multi-leaf stone masonry elements is discussed in the paper. Shaking table experiments on two stone masonry buildings, tested before and after grout injection, have been performed. The paper focuses on the analysis of both the recorded accelerations and related displacements, at the bottom and at each further storey. This leads to evaluate the stiffness of the unstrengthened and injected structures. The input at increasing PGA allowed the stiffness decay to be studied, simulating a gradual damaging of the structures. These results were also interpreted in the light of both computed frequencies and mode shapes. Finally, the comparison among these results, obtained from all the models, allows to deepen the knowledge concerning the effects induced by the lime-based grout injection and on its capability to modify the dynamic behaviour, when intervening on a damaged (repairing) or on an undamaged (strengthening) structure.

scholarly journals Modelling imperfections in unreinforced masonry structures: Discrete element simulations and scale model experiments of a pavilion vault

2021 ◽  
Vol 228 ◽  
pp. 111499
Author(s):  
Alessandro Dell'Endice ◽  
Antonino Iannuzzo ◽  
Matthew J. DeJong ◽  
Tom Van Mele ◽  
Philippe Block
Keyword(s):  
Discrete Element ◽  
Unreinforced Masonry ◽  
Scale Model ◽  
Masonry Structures ◽  
Model Experiments ◽  
Discrete Element Simulations

Study on the shear wall structure with combined form of replaceable devices

2017 ◽  
Vol 21 (9) ◽  
pp. 1327-1348
Author(s):  
Cong Chen ◽  
Renjie Xiao ◽  
Xilin Lu ◽  
Yun Chen
Keyword(s):  
Shear Walls ◽  
Shear Wall ◽  
Performance Comparison ◽  
Wall Structure ◽  
Structural Part ◽  
Coupled Shear Wall ◽  
Wall Structures ◽  
Strength And Stiffness ◽  
Energy Dissipated ◽  
Resilient Structure

Structure with replaceable devices is a type of earthquake resilient structure developed to restore the structure immediately after strong earthquakes. Current researches focus on one type of the replaceable device located in the structural part that is most likely to be damaged; however, plastic deformation would not be limited in a specific part but expand to other parts. To concentrate possible damage in shear wall structures, combined form of replaceable devices was introduced in this article. Based on previous studies, combined form of replaceable coupling beam and replaceable wall foot was used in a coupled shear wall. Influences of the dimension and location of the replaceable devices to the strength and stiffness of the shear wall were investigated through numerical modeling, which was verified by experimental data. Performance comparison between the shear walls with one type and combined form of replaceable devices and the conventional coupled shear wall was performed. In general, the shear wall with combined form of replaceable devices is shown to be better energy dissipated, and proper dimensions and locations of the replaceable devices should be determined.

The Benefits of a Seismic Retrofit Program for Commercial Unreinforced Masonry Structures: Salt Lake County, Utah

1993 ◽  
Vol 9 (1) ◽  
pp. 1-10
Author(s):  
Philip C. Emmi ◽  
Carl A. Horton
Keyword(s):  
Salt Lake ◽  
Exposure Period ◽  
Seismic Retrofit ◽  
Unreinforced Masonry ◽  
Masonry Structures ◽  
Damage Functions ◽  
Lake County ◽  
Evaluation Time ◽  
Comparative Risk ◽  
Uniform Code

This paper assesses the benefits of a seismic retrofit program for commercial unreinforced masonry structures (CURMs) in Salt Lake County, Utah. A comparative risk assessment embedded in a geographic information systems is the method used. A policy evaluation time horizon of twenty years is set. Future rates of demolition and rehabilitation, with and without a retrofit policy, are assumed. Damage functions for ordinary and retrofitted URMs are used to assess losses having a 10 percent chance of being exceeded over a 50-year exposure period. With a retrofit program, expected losses are reduced by 57 percent or more than a quarter billion dollars when compared to the no-policy scenario. Expected injuries and fatalities are reduced by more than 80 percent. These are minimal benefits expected from enforcement of the seismic provisions of the Uniform Code of Building Conservation.

scholarly journals Curable Area Substantiation of Self-Healing in Concrete Using Neutral Axis

2019 ◽  
Vol 9 (8) ◽  
pp. 1537 ◽  
Author(s):  
Choonghyun Kang ◽  
Taewan Kim
Keyword(s):  
Neutral Axis ◽  
The Self ◽  
Strain Gauges ◽  
Self Healing ◽  
Distinct Area ◽  
Before And After ◽  
Strength And Stiffness ◽  
Underlying Mechanisms ◽  
Healing Assessment ◽  
Physical Recovery

The self-healing nature of concrete has been proved in many studies using various methods. However, the underlying mechanisms and the distinct area of self-healing have not been identified in detail. This study focuses on the limits of the area of self-healing. A bending specimen with a notch is used herein, and its flexural strength and stiffness before and after healing are compared and used for self-healing assessment. In addition, the neutral axis of the specimen was measured using successive strain gauges attached to the crack propagation part. Although the strength and stiffness of the concrete recovered after self-healing, the change in the location of the neutral axis before and after healing was insignificant, which indicates that physical recovery did not occur for once-opened crack areas.

Grout Injection Effect on the Shear Behavior of FRCM Strengthened Stone Masonry Panels

2019 ◽  
Vol 817 ◽  
pp. 552-559
Author(s):  
Francesca Ferretti ◽  
Andrea Incerti ◽  
Anna Rosa Tilocca ◽  
Claudio Mazzotti
Keyword(s):  
Shear Capacity ◽  
Stone Masonry ◽  
Masonry Structures ◽  
Compression Tests ◽  
Grout Injection ◽  
Structural Element ◽  
Diagonal Compression ◽  
Two Samples ◽  
Injection Effect

During the last decades, several seismic phenomena have shown the high vulnerability of existing stone masonry structures subject to horizontal actions. Innovative composite materials, such as Fiber Reinforced Cementitious Matrix (FRCM), can be adopted for the retrofitting of masonry structures. The use of these innovative FRCM systems is usually combined with a more traditional retrofitting technique: grout injection. It allows to restore or improve the transversal connection between wall leaves, ensuring a monolithic behavior of the structural element. The objective of this research was to analyze the effect of the quality of the grout injection on the shear response of FRCM strengthened stone masonry panels. Results from an experimental campaign, where stone masonry specimens were subject to diagonal compression tests, are therefore presented in this paper. Two samples were subject to grout injection and one of them was strengthened with Steel Reinforced Grout (SRG). Comparisons between the experimental results showed that grout injection alone, if correctly executed, could determine a significant improvement in the shear capacity of masonry panels. The application of the FRCM strengthening system could further enhance the behavior of the samples, especially influencing the failure mode. Comparisons with analytical formulations for the evaluation of the capacity of strengthened walls are also presented.

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